//! A business's needs, stated apart from how its pages word them.
//!
//! A content repo may ship a `needs.yaml` at its root: each *need* says
//! who wants what, where they enter, which bucket the answer must land
//! in, and which group has to be able to carry it to a finished state.
//! Two things are checked against it:
//!
//! - **Structure** (`check`): deterministic. A path of submissions
//!   leads from the entry page to the bucket, within an effort budget;
//!   the handling group has a desk over that bucket; every finished
//!   state is reachable through the moves that desk offers, and no
//!   record strands on the way.
//! - **Wording** (`tasks` / `score`): each *persona* is a visitor in
//!   their own words. Every page on their path becomes one typed
//!   `choice` question for an external answering engine - the page's
//!   question, its alternatives as the options - and the engine's picks
//!   are scored against the alternatives that actually meet the need.
//!   A misroute is a wording defect: the page said one thing and the
//!   visitor heard another.
//!
//! The engine is deliberately outside this crate: tasks go out as
//! JSONL, answers come back as JSONL, so any classifier or LLM can sit
//! in between and be compared on the same tasks.

use std::collections::{BTreeMap, HashMap, HashSet, VecDeque};

use serde::{Deserialize, Serialize};

use portal::aggregates::AggregateSchema;
use portal::content::{action_target_id, Alternative, Question};

#[derive(Debug, Default, Deserialize)]
#[serde(deny_unknown_fields)]
pub struct NeedsFile {
    #[serde(default)]
    pub needs: Vec<Need>,
    #[serde(default)]
    pub personas: Vec<Persona>,
}

#[derive(Debug, Deserialize)]
#[serde(deny_unknown_fields)]
pub struct Need {
    pub id: String,
    /// The kind of visitor - prose, for the reader of the report.
    pub who: String,
    pub wants: String,
    /// The page they arrive on.
    #[serde(default = "root")]
    pub enters: String,
    /// The group they hold when they arrive; unset means anonymous.
    #[serde(default)]
    pub enters_as: Option<String>,
    /// The alternative on the entry page that serves this need, when
    /// several record into the same bucket.
    #[serde(default)]
    pub via: Option<String>,
    /// The bucket their answer must be recorded into.
    pub lands_in: String,
    /// The group that must be able to see the record and move it.
    pub handled_by: String,
    /// The states that count as handled.
    pub done_when: Vec<String>,
    /// Submissions the visitor may be asked for before the record
    /// exists.
    #[serde(default = "default_max_steps")]
    pub max_steps: usize,
    /// Required fields across the whole path - the onboarding effort
    /// budget.
    #[serde(default)]
    pub max_fields: Option<usize>,
    /// Declared, and knowingly not open yet: what is missing reports
    /// as a warning, so the gap stays visible without failing CI.
    #[serde(default)]
    pub planned: bool,
    /// Each state of the bucket in plain words, in the site's
    /// language, for the scorer: state ids are ASCII, and a Norwegian
    /// `ikke_lost` reads as English to a model.
    #[serde(default)]
    pub stage_words: std::collections::BTreeMap<String, String>,
    /// The finished states that are a good outcome for the business -
    /// a subset of `done_when`. "lost" is finished; "won" is success.
    /// What a simulation or a live bucket report counts toward.
    #[serde(default)]
    pub success: Vec<String>,
    /// Every stage the business said a case goes through, in its own
    /// order, first to last. Written from how the business describes
    /// its work, before any state machine exists, so that a machine
    /// which quietly skips a stage ("we go and look, then we quote"
    /// becoming open -> quoted) fails instead of passing.
    #[serde(default)]
    pub stages: Vec<String>,
    /// Other groups whose desks carry some of this need's moves: a
    /// site manager closing what a project manager opened. Their
    /// buttons count toward reaching `done_when` exactly as
    /// `handled_by`'s do. `handled_by` must still hold a desk of its
    /// own - someone has to be answerable for the record.
    #[serde(default)]
    pub also_moved_by: Vec<String>,
}

fn root() -> String {
    "/".to_string()
}

fn default_max_steps() -> usize {
    2
}

#[derive(Debug, Deserialize)]
#[serde(deny_unknown_fields)]
pub struct Persona {
    pub id: String,
    pub need: String,
    /// The visitor's situation in their own words - never the page's.
    pub text: String,
}

pub fn parse(raw: &str) -> anyhow::Result<NeedsFile> {
    serde_yaml::from_str(raw).map_err(|e| anyhow::anyhow!("parsing needs.yaml: {e}"))
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum Level {
    Fail,
    Warn,
}

#[derive(Debug)]
pub struct Finding {
    pub need: String,
    pub level: Level,
    pub message: String,
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Step {
    pub page: String,
    pub alternative: String,
}

/// One alternative on a page that still meets the need, with the
/// cheapest way on from it.
struct Viable {
    alternative: String,
    path: Vec<Step>,
    fields: usize,
    records_with_action: Option<bool>,
}

type Questions = HashMap<String, Question>;

fn visible(q: &Question, as_group: Option<&str>) -> bool {
    match &q.qualifies {
        None => true,
        Some(group) => as_group == Some(group.as_str()),
    }
}

/// What a person has to fill in: required fields, less the ones that
/// carry rather than ask - a `record` naming the case an answer is
/// about, a `hidden` preset - which cost nobody anything.
fn required_fields(alt: &Alternative) -> usize {
    alt.features
        .iter()
        .flat_map(|f| &f.requirements)
        .filter(|r| !r.optional && r.kind != "record" && r.kind != "hidden")
        .count()
}

/// The alternatives on `page` from which the need is still met within
/// `remaining` submissions.
fn viable(
    questions: &Questions,
    need: &Need,
    page: &Question,
    remaining: usize,
    entry: bool,
    include_disabled: bool,
    trail: &mut Vec<String>,
) -> Vec<Viable> {
    let mut out = Vec::new();
    if remaining == 0 {
        return out;
    }
    for alt in page.alternatives.iter().filter(|a| include_disabled || !a.disabled) {
        if entry && need.via.as_deref().is_some_and(|via| via != alt.name) {
            continue;
        }
        let step = Step {
            page: page.id.clone(),
            alternative: alt.name.clone(),
        };
        let fields = required_fields(alt);
        if alt.record_as.as_deref() == Some(need.lands_in.as_str()) {
            out.push(Viable {
                alternative: alt.name.clone(),
                path: vec![step],
                fields,
                records_with_action: Some(alt.action.is_some()),
            });
            continue;
        }
        let Some(target) = alt
            .action
            .as_deref()
            .and_then(|a| action_target_id(questions, a))
            .and_then(|id| questions.get(&id))
        else {
            continue;
        };
        if trail.contains(&target.id) || !visible(target, need.enters_as.as_deref()) {
            continue;
        }
        trail.push(target.id.clone());
        let onward = viable(questions, need, target, remaining - 1, false, include_disabled, trail);
        trail.pop();
        if let Some(best) = onward.into_iter().min_by_key(|v| (v.path.len(), v.fields)) {
            let mut path = vec![step];
            path.extend(best.path);
            out.push(Viable {
                alternative: alt.name.clone(),
                path,
                fields: fields + best.fields,
                records_with_action: best.records_with_action,
            });
        }
    }
    out
}

fn entry_viable(questions: &Questions, need: &Need, include_disabled: bool) -> Option<Vec<Viable>> {
    let page = questions.get(&need.enters)?;
    let mut trail = vec![page.id.clone()];
    Some(viable(questions, need, page, need.max_steps, true, include_disabled, &mut trail))
}

/// The cheapest path that meets the need, if any.
pub fn path_for(questions: &Questions, need: &Need) -> Option<Vec<Step>> {
    entry_viable(questions, need, false)?
        .into_iter()
        .min_by_key(|v| (v.path.len(), v.fields))
        .map(|v| v.path)
}

struct Desk {
    page: String,
    group: Option<String>,
    /// (from, to, button label)
    moves: Vec<(String, String, String)>,
}

fn desks_over(questions: &Questions, bucket: &str) -> Vec<Desk> {
    let mut desks = Vec::new();
    for q in questions.values() {
        for resource in q
            .alternatives
            .iter()
            .flat_map(|a| &a.features)
            .filter_map(|f| f.resource.as_ref())
            .filter(|r| r.bucket() == Some(bucket))
        {
            desks.push(Desk {
                page: q.id.clone(),
                group: resource.requires_group.clone().or_else(|| q.qualifies.clone()),
                moves: resource
                    .transitions
                    .iter()
                    .map(|t| (t.from.clone(), t.to.clone(), t.label.clone()))
                    .collect(),
            });
        }
    }
    desks.sort_by(|a, b| a.page.cmp(&b.page));
    desks
}

/// Self-service moves into `bucket` - a visitor holding their own
/// record's link, no group involved (unsubscribe).
fn self_moves(questions: &Questions, bucket: &str) -> Vec<String> {
    questions
        .values()
        .flat_map(|q| &q.alternatives)
        .filter_map(|a| a.self_transition.as_ref())
        .filter(|s| s.bucket == bucket)
        .map(|s| s.to.clone())
        .collect()
}

/// Structural check of every need. `Fail` findings mean the business
/// need is not met by the content as written.
pub fn check(
    file: &NeedsFile,
    questions: &Questions,
    aggregates: &HashMap<String, AggregateSchema>,
) -> Vec<Finding> {
    let mut findings = Vec::new();
    let mut seen = HashSet::new();
    for need in &file.needs {
        let mut report = |level: Level, message: String| {
            findings.push(Finding {
                need: need.id.clone(),
                level: if need.planned { Level::Warn } else { level },
                message: if need.planned && level == Level::Fail {
                    format!("planned, not met yet: {message}")
                } else {
                    message
                },
            })
        };
        if !seen.insert(need.id.as_str()) {
            report(Level::Fail, "declared more than once".to_string());
            continue;
        }

        // The visitor's side: can they get their answer recorded?
        match questions.get(&need.enters) {
            None => report(Level::Fail, format!("entry page {:?} does not exist", need.enters)),
            Some(page) if !visible(page, need.enters_as.as_deref()) => report(
                Level::Fail,
                format!(
                    "entry page {:?} is gated on {:?}, which this visitor does not hold",
                    need.enters, page.qualifies
                ),
            ),
            Some(page) => {
                if page.responsible.is_none() {
                    report(
                        Level::Warn,
                        format!("entry page {:?} names no one responsible to turn to", need.enters),
                    );
                }
                let best = entry_viable(questions, need, false)
                    .unwrap_or_default()
                    .into_iter()
                    .min_by_key(|v| (v.path.len(), v.fields));
                match best {
                    None if entry_viable(questions, need, true).is_some_and(|v| !v.is_empty()) => {
                        let blocked = entry_viable(questions, need, true)
                            .unwrap_or_default()
                            .into_iter()
                            .min_by_key(|v| (v.path.len(), v.fields))
                            .map(|v| v.path)
                            .unwrap_or_default();
                        let at = blocked
                            .iter()
                            .find(|s| {
                                questions[&s.page]
                                    .alternatives
                                    .iter()
                                    .any(|a| a.name == s.alternative && a.disabled)
                            })
                            .map(|s| format!("{:?} on {}", s.alternative, s.page))
                            .unwrap_or_default();
                        report(
                            Level::Fail,
                            format!(
                                "the path exists but is closed: {at} is `disabled`, so the answer is advertised and refused"
                            ),
                        )
                    }
                    None => report(
                        Level::Fail,
                        format!(
                            "no path from {:?}{} records into {:?} within {} submission(s)",
                            need.enters,
                            need.via
                                .as_ref()
                                .map(|v| format!(" via {v:?}"))
                                .unwrap_or_default(),
                            need.lands_in,
                            need.max_steps
                        ),
                    ),
                    Some(best) => {
                        if let Some(budget) = need.max_fields {
                            if best.fields > budget {
                                report(
                                    Level::Fail,
                                    format!(
                                        "the path asks for {} required field(s), over the budget of {budget}",
                                        best.fields
                                    ),
                                );
                            }
                        }
                        if best.records_with_action == Some(false) {
                            report(
                                Level::Warn,
                                "the recording alternative has no `action` - the visitor is never told what happens next".to_string(),
                            );
                        }
                    }
                }
            }
        }

        // The business's side: can the handling group finish it?
        let Some(schema) = aggregates.get(&need.lands_in) else {
            report(
                Level::Fail,
                format!("aggregates.yaml declares no state machine for {:?}", need.lands_in),
            );
            continue;
        };
        let desks = desks_over(questions, &need.lands_in);
        let own: Vec<&Desk> = desks
            .iter()
            .filter(|d| {
                d.group.as_deref().is_some_and(|g| g == need.handled_by || need.also_moved_by.iter().any(|m| m == g))
            })
            .collect();
        if !desks.iter().any(|d| d.group.as_deref() == Some(need.handled_by.as_str())) {
            let others: Vec<String> = desks
                .iter()
                .map(|d| format!("{} ({})", d.page, d.group.as_deref().unwrap_or("ungated")))
                .collect();
            report(
                Level::Fail,
                format!(
                    "no desk gated on {:?} reads {:?}{}",
                    need.handled_by,
                    need.lands_in,
                    if others.is_empty() {
                        String::new()
                    } else {
                        format!(" - it is read by {}", others.join(", "))
                    }
                ),
            );
            continue;
        }
        let selfs = self_moves(questions, &need.lands_in);
        let exits = |state: &str| -> Vec<String> {
            let allowed = schema.allowed(state);
            let mut to: Vec<String> = own
                .iter()
                .flat_map(|d| &d.moves)
                .filter(|(from, to, _)| from == state && allowed.contains(to))
                .map(|(_, to, _)| to.clone())
                .collect();
            to.extend(selfs.iter().filter(|to| allowed.contains(to)).cloned());
            to
        };
        let done: HashSet<&str> = need.done_when.iter().map(String::as_str).collect();
        // Reachability walks the whole machine (a finished state may
        // lead on to another: subscribed, then unsubscribed). Stranding
        // only counts on the way to the first finished state - what
        // happens to a handled record afterwards is not this need.
        let mut reached: HashSet<String> = HashSet::from([schema.initial.clone()]);
        let mut queue = VecDeque::from([(schema.initial.clone(), false)]);
        let mut stranded = Vec::new();
        while let Some((state, past_done)) = queue.pop_front() {
            let past_done = past_done || done.contains(state.as_str());
            let next = exits(&state);
            if next.is_empty() && !past_done {
                stranded.push(state.clone());
            }
            for to in next {
                if reached.insert(to.clone()) {
                    queue.push_back((to, past_done));
                }
            }
        }
        for state in &need.done_when {
            if !schema.has_state(state) {
                report(
                    Level::Fail,
                    format!("done_when names {state:?}, which {:?} has no such state", need.lands_in),
                );
            } else if !reached.contains(state) {
                report(
                    Level::Fail,
                    format!(
                        "{:?} cannot move a record to {state:?} - no desk of theirs offers the moves",
                        need.handled_by
                    ),
                );
            }
        }
        for stage in &need.stages {
            if !schema.has_state(stage) {
                report(
                    Level::Fail,
                    format!(
                        "the business describes a stage {stage:?} that {:?} has no state for",
                        need.lands_in
                    ),
                );
            } else if !reached.contains(stage) {
                report(
                    Level::Fail,
                    format!(
                        "stage {stage:?} exists but {:?} is offered no moves that reach it",
                        need.handled_by
                    ),
                );
            }
        }
        for state in &need.success {
            if !need.done_when.contains(state) {
                report(
                    Level::Fail,
                    format!("success names {state:?}, which is not one of done_when"),
                );
            }
        }
        stranded.sort();
        for state in stranded {
            report(
                Level::Fail,
                format!(
                    "records strand in {state:?}: {:?} is offered no move out of it",
                    need.handled_by
                ),
            );
        }
    }

    let need_ids: HashSet<&str> = file.needs.iter().map(|n| n.id.as_str()).collect();
    for persona in &file.personas {
        if !need_ids.contains(persona.need.as_str()) {
            findings.push(Finding {
                need: persona.need.clone(),
                level: Level::Fail,
                message: format!("persona {:?} points at a need that is not declared", persona.id),
            });
        }
    }
    findings
}

/// Everything a simulation of the business needs, resolved: each
/// need's path with the choice on every page and the form that gets
/// filled, each bucket's state machine with the buttons every desk
/// offers, and the personas. Portal resolves it because only portal
/// loads content the way the runtime does (derived ids, relative
/// refs, sections); whoever simulates reads plain JSON.
pub fn sim_model(
    file: &NeedsFile,
    questions: &Questions,
    aggregates: &HashMap<String, AggregateSchema>,
) -> serde_json::Value {
    use serde_json::json;
    let mut needs = Vec::new();
    let mut buckets = serde_json::Map::new();
    for need in &file.needs {
        let Some(path) = path_for(questions, need) else {
            continue;
        };
        let steps: Vec<serde_json::Value> = path
            .iter()
            .enumerate()
            .map(|(i, step)| {
                let page = &questions[&step.page];
                let mut trail: Vec<String> = path[..=i].iter().map(|s| s.page.clone()).collect();
                let expect: Vec<String> =
                    viable(questions, need, page, need.max_steps - i, i == 0, false, &mut trail)
                        .into_iter()
                        .map(|v| v.alternative)
                        .collect();
                let fields: Vec<serde_json::Value> = page
                    .alternatives
                    .iter()
                    .find(|a| a.name == step.alternative)
                    .into_iter()
                    .flat_map(|a| &a.features)
                    .flat_map(|f| &f.requirements)
                    .map(|r| {
                        json!({
                            "name": r.name,
                            "label": r.label.clone().unwrap_or_else(|| r.name.clone()),
                            "type": r.kind,
                            "optional": r.optional,
                            "options": r.options,
                        })
                    })
                    .collect();
                json!({
                    "page": step.page,
                    "question": page.name,
                    "context": page_context(page),
                    "options": page.alternatives.iter().filter(|a| !a.disabled && leads_somewhere(a)).map(|a| json!({
                        "name": a.name,
                        "description": plain(&a.description),
                    })).collect::<Vec<_>>(),
                    "expect": expect,
                    "alternative": step.alternative,
                    "fields": fields,
                })
            })
            .collect();
        needs.push(json!({
            "id": need.id,
            "who": need.who,
            "wants": need.wants,
            "enters_as": need.enters_as,
            "lands_in": need.lands_in,
            "handled_by": need.handled_by,
            "done_when": need.done_when,
            "success": need.success,
            "steps": steps,
        }));
        if let Some(schema) = aggregates.get(&need.lands_in) {
            buckets.entry(need.lands_in.clone()).or_insert_with(|| {
                json!({
                    "initial": schema.initial,
                    "transitions": schema.transitions,
                    "words": need.stage_words,
                    "desks": desks_over(questions, &need.lands_in).iter().map(|d| json!({
                        "page": d.page,
                        "group": d.group,
                        "moves": d.moves.iter().map(|(from, to, label)| json!({
                            "from": from, "to": to, "label": label,
                        })).collect::<Vec<_>>(),
                    })).collect::<Vec<_>>(),
                    "self_moves": self_moves(questions, &need.lands_in),
                })
            });
        }
    }
    json!({
        "needs": needs,
        "buckets": buckets,
        "personas": file.personas.iter().map(|p| json!({
            "id": p.id, "need": p.need, "text": plain(&p.text),
        })).collect::<Vec<_>>(),
    })
}

/// One decision for the answering engine - the shape is laya's
/// `predict(state, questions)` input, so an adapter is a loop and
/// nothing more; any other engine reads the same fields.
#[derive(Debug, Serialize)]
pub struct Task {
    pub id: String,
    pub persona: String,
    pub need: String,
    pub page: String,
    pub state: BTreeMap<&'static str, String>,
    pub questions: BTreeMap<&'static str, ChoiceQuestion>,
    /// Every alternative that still meets the need from here. The
    /// engine never sees this.
    pub expect: Vec<String>,
}

#[derive(Debug, Serialize)]
pub struct ChoiceQuestion {
    #[serde(rename = "type")]
    pub kind: &'static str,
    pub instructions: String,
    pub criteria: BTreeMap<String, String>,
}

fn plain(text: &str) -> String {
    text.split_whitespace().collect::<Vec<_>>().join(" ")
}

/// A card a visitor can act on: it leads to a page, records an
/// answer, or moves a record. A card with none of those is read, not
/// picked - the opener that says what the business does, the look
/// around - and is context on the page, never an option.
pub fn leads_somewhere(a: &Alternative) -> bool {
    a.action.is_some() || a.record_as.is_some() || a.self_transition.is_some()
}

/// What the page says before its options: every card that leads
/// nowhere, its heading, description and features, as one line each.
pub fn page_context(page: &Question) -> String {
    page.alternatives
        .iter()
        .filter(|a| !a.disabled && !leads_somewhere(a))
        .map(|a| {
            let mut line = a.name.clone();
            let description = plain(&a.description);
            if !description.is_empty() {
                line.push_str(&format!(": {description}"));
            }
            for f in &a.features {
                let text = plain(&f.description);
                match (f.name.trim().is_empty(), text.is_empty()) {
                    (true, true) => {}
                    (true, false) => line.push_str(&format!(" {text}")),
                    (false, true) => line.push_str(&format!(" {}.", f.name.trim())),
                    (false, false) => line.push_str(&format!(" {}: {text}", f.name.trim())),
                }
            }
            line
        })
        .collect::<Vec<_>>()
        .join("\n")
}

/// Every (persona, page-on-their-path) pair with a real choice on it.
/// `skim` shows the engine only each alternative's heading - what a
/// visitor who never reads the description has to go on.
pub fn tasks(file: &NeedsFile, questions: &Questions, skim: bool) -> Vec<Task> {
    let mut out = Vec::new();
    for persona in &file.personas {
        let Some(need) = file.needs.iter().find(|n| n.id == persona.need) else {
            continue;
        };
        let Some(path) = path_for(questions, need) else {
            continue;
        };
        for (i, step) in path.iter().enumerate() {
            let page = &questions[&step.page];
            let open: Vec<&Alternative> = page.alternatives.iter().filter(|a| !a.disabled && leads_somewhere(a)).collect();
            if open.len() < 2 {
                continue;
            }
            let context = page_context(page);
            let mut trail: Vec<String> = path[..=i].iter().map(|s| s.page.clone()).collect();
            let expect: Vec<String> = viable(questions, need, page, need.max_steps - i, i == 0, false, &mut trail)
                .into_iter()
                .map(|v| v.alternative)
                .collect();
            let criteria = open
                .iter()
                .map(|a| {
                    let description = plain(&a.description);
                    (
                        a.name.clone(),
                        if skim || description.is_empty() { a.name.clone() } else { description },
                    )
                })
                .collect();
            out.push(Task {
                id: format!("{}@{}", persona.id, step.page),
                persona: persona.id.clone(),
                need: need.id.clone(),
                page: step.page.clone(),
                state: if context.is_empty() {
                    BTreeMap::from([("body", plain(&persona.text))])
                } else {
                    BTreeMap::from([("body", plain(&persona.text)), ("page", context)])
                },
                questions: BTreeMap::from([(
                    "pick",
                    ChoiceQuestion {
                        kind: "choice",
                        instructions: format!(
                            "A visitor reads the page question {:?}. Which alternative do they choose?",
                            page.name
                        ),
                        criteria,
                    },
                )]),
                expect,
            });
        }
    }
    out
}

#[derive(Debug, Deserialize)]
pub struct Answer {
    pub id: String,
    pub choice: String,
    #[serde(default)]
    pub confidence: Option<f64>,
}

#[derive(Debug, Default)]
pub struct Score {
    pub total: usize,
    pub correct: usize,
    /// (task id, picked, expected, confidence)
    pub misroutes: Vec<(String, String, Vec<String>, Option<f64>)>,
    /// Right, but the engine was under `hesitant_below` - wording that
    /// works and is still close to a coin flip.
    pub hesitant: Vec<(String, f64)>,
    pub unanswered: Vec<String>,
}

impl Score {
    pub fn accuracy(&self) -> f64 {
        if self.total == 0 {
            1.0
        } else {
            self.correct as f64 / self.total as f64
        }
    }
}

pub fn score(tasks: &[Task], answers: &[Answer], hesitant_below: f64) -> Score {
    let by_id: HashMap<&str, &Answer> = answers.iter().map(|a| (a.id.as_str(), a)).collect();
    let mut score = Score {
        total: tasks.len(),
        ..Score::default()
    };
    for task in tasks {
        match by_id.get(task.id.as_str()) {
            None => score.unanswered.push(task.id.clone()),
            Some(answer) if task.expect.contains(&answer.choice) => {
                score.correct += 1;
                if let Some(c) = answer.confidence.filter(|c| *c < hesitant_below) {
                    score.hesitant.push((task.id.clone(), c));
                }
            }
            Some(answer) => score.misroutes.push((
                task.id.clone(),
                answer.choice.clone(),
                task.expect.clone(),
                answer.confidence,
            )),
        }
    }
    score
}

#[cfg(test)]
mod tests {
    use super::*;
    use portal::aggregates::parse_aggregates_yaml;
    use portal::content::build_questions;

    fn site(desk_moves: &str) -> (Questions, HashMap<String, AggregateSchema>) {
        let files = vec![
            (
                "index.yaml".to_string(),
                "name: What are you here for?\nresponsible: { name: A, contact: a@b.c }\nalternatives:\n  - name: Hire us\n    description: Bring a problem.\n    action: /thanks\n    record_as: projects\n    features:\n      - name: Brief\n        requirements:\n          - name: email\n            type: email\n          - name: brief\n            type: textarea\n          - name: budget\n            optional: true\n  - name: Follow along\n    description: Notes by mail.\n    action: /thanks\n    record_as: subscribers\n".to_string(),
            ),
            ("thanks.yaml".to_string(), "name: Thanks\nfollowup: true\n".to_string()),
            (
                "desk/index.yaml".to_string(),
                format!("name: Desk\nqualifies: owners\nalternatives:\n  - name: Projects\n    features:\n      - name: \"\"\n        resource:\n          source: {{ kind: kv, bucket: projects }}\n          requires_group: owners\n          transitions:\n{desk_moves}"),
            ),
        ];
        let aggregates = parse_aggregates_yaml(
            "aggregates:\n  - bucket: projects\n    initial: open\n    states:\n      open: { event: submitted }\n      quoted: { event: quoted }\n      won: { event: won }\n      lost: { event: lost }\n    transitions:\n      open: [quoted, lost]\n      quoted: [won, lost]\n  - bucket: subscribers\n    attended_by: a mailer\n    initial: open\n    states:\n      open: { event: subscribed }\n    transitions: {}\n",
        )
        .unwrap();
        (build_questions(&files).unwrap(), aggregates)
    }

    const FULL_DESK: &str = "            - { to: quoted, label: Quote }\n            - { to: lost, label: Lose }\n            - { from: quoted, to: won, label: Win }\n            - { from: quoted, to: lost, label: Lose }\n";

    fn needs(extra: &str) -> NeedsFile {
        parse(&format!(
            "needs:\n  - id: hire\n    who: a client\n    wants: work done\n    lands_in: projects\n    handled_by: owners\n    done_when: [won, lost]\n{extra}personas:\n  - id: founder\n    need: hire\n    text: I need someone to build our booking tool.\n"
        ))
        .unwrap()
    }

    fn fails(findings: &[Finding]) -> Vec<&str> {
        findings
            .iter()
            .filter(|f| f.level == Level::Fail)
            .map(|f| f.message.as_str())
            .collect()
    }

    #[test]
    fn a_met_need_is_silent() {
        let (questions, aggregates) = site(FULL_DESK);
        let findings = check(&needs("    max_fields: 2\n"), &questions, &aggregates);
        assert!(findings.is_empty(), "{findings:?}");
    }

    #[test]
    fn effort_budget_counts_required_fields_only() {
        let (questions, aggregates) = site(FULL_DESK);
        let findings = check(&needs("    max_fields: 1\n"), &questions, &aggregates);
        assert_eq!(fails(&findings), vec!["the path asks for 2 required field(s), over the budget of 1"]);
        // A field that carries rather than asks is not effort: the
        // record an answer is about arrives on the link.
        let (mut questions, aggregates) = site(FULL_DESK);
        let front = questions.get_mut("/").unwrap();
        let brief = &mut front.alternatives[0].features[0].requirements;
        let mut carrier = brief[0].clone();
        carrier.name = "case".into();
        carrier.kind = "record".into();
        carrier.of = Some("projects".into());
        carrier.optional = false;
        brief.push(carrier);
        let findings = check(&needs("    max_fields: 2\n"), &questions, &aggregates);
        assert!(fails(&findings).is_empty(), "{findings:?}");
    }

    #[test]
    fn a_desk_missing_a_move_strands_records_and_cannot_finish() {
        // The desk can quote, but never close a quoted job.
        let (questions, aggregates) = site("            - { to: quoted, label: Quote }\n            - { to: lost, label: Lose }\n");
        let findings = check(&needs(""), &questions, &aggregates);
        assert_eq!(
            fails(&findings),
            vec![
                "\"owners\" cannot move a record to \"won\" - no desk of theirs offers the moves",
                "records strand in \"quoted\": \"owners\" is offered no move out of it",
            ]
        );
    }

    #[test]
    fn a_finished_state_may_lead_on_to_another() {
        // quoted counts as handled here, yet won must still be
        // reachable past it; lost-after-quoted is not this need's
        // business, so nothing strands.
        let (questions, aggregates) = site(FULL_DESK);
        let mut file = needs("");
        file.needs[0].done_when = vec!["quoted".to_string(), "won".to_string(), "lost".to_string()];
        let findings = check(&file, &questions, &aggregates);
        assert!(findings.is_empty(), "{findings:?}");
    }

    #[test]
    fn a_disabled_alternative_is_named_as_the_reason() {
        let (mut questions, aggregates) = site(FULL_DESK);
        questions.get_mut("/").unwrap().alternatives[0].disabled = true;
        let findings = check(&needs(""), &questions, &aggregates);
        assert_eq!(
            fails(&findings),
            vec!["the path exists but is closed: \"Hire us\" on / is `disabled`, so the answer is advertised and refused"]
        );
    }

    #[test]
    fn success_must_be_a_finished_state_and_the_sim_model_carries_the_whole_flow() {
        let (questions, aggregates) = site(FULL_DESK);
        let mut file = needs("    success: [won]\n");
        assert!(check(&file, &questions, &aggregates).is_empty());

        let model = sim_model(&file, &questions, &aggregates);
        let need = &model["needs"][0];
        assert_eq!(need["success"][0], "won");
        let step = &need["steps"][0];
        assert_eq!(step["question"], "What are you here for?");
        assert_eq!(step["expect"][0], "Hire us");
        assert_eq!(step["options"].as_array().unwrap().len(), 2);
        // The form the visitor fills, required and optional alike.
        let fields = step["fields"].as_array().unwrap();
        assert_eq!(fields.len(), 3);
        assert_eq!(fields[2]["optional"], true);
        // The desk's buttons, labelled, per state.
        let moves = model["buckets"]["projects"]["desks"][0]["moves"].as_array().unwrap();
        assert!(moves.iter().any(|m| m["from"] == "quoted" && m["to"] == "won" && m["label"] == "Win"));
        assert_eq!(model["buckets"]["projects"]["initial"], "open");
        assert_eq!(model["personas"][0]["id"], "founder");

        // A stage the business named must exist as a state.
        file.needs[0].stages = vec!["open".into(), "surveyed".into(), "quoted".into()];
        assert_eq!(
            fails(&check(&file, &questions, &aggregates)),
            vec!["the business describes a stage \"surveyed\" that \"projects\" has no state for"]
        );
        file.needs[0].stages = vec!["open".into(), "quoted".into(), "won".into()];
        assert!(check(&file, &questions, &aggregates).is_empty());

        file.needs[0].success = vec!["quoted".to_string()];
        assert_eq!(
            fails(&check(&file, &questions, &aggregates)),
            vec!["success names \"quoted\", which is not one of done_when"]
        );
    }

    #[test]
    fn a_need_can_be_carried_by_more_than_one_groups_desk() {
        // owners may only quote or lose; closing a quoted job is the
        // site managers' button, on a desk of their own.
        let (mut questions, aggregates) = site("            - { to: quoted, label: Quote }\n            - { to: lost, label: Lose }\n");
        let more = build_questions(&[(
            "site/index.yaml".to_string(),
            "name: Site desk\nqualifies: site_managers\nalternatives:\n  - name: Projects\n    features:\n      - name: \"\"\n        resource:\n          source: { kind: kv, bucket: projects }\n          requires_group: site_managers\n          transitions:\n            - { from: quoted, to: won, label: Win }\n            - { from: quoted, to: lost, label: Lose }\n".to_string(),
        )])
        .unwrap();
        questions.extend(more);

        let mut file = needs("");
        // Alone, owners cannot finish it...
        assert_eq!(fails(&check(&file, &questions, &aggregates)).len(), 2);
        // ...with the site managers' buttons counted, they can.
        file.needs[0].also_moved_by = vec!["site_managers".to_string()];
        assert!(check(&file, &questions, &aggregates).is_empty());
        // But someone has to be answerable: handled_by needs its own desk.
        file.needs[0].handled_by = "nobody".to_string();
        assert!(fails(&check(&file, &questions, &aggregates))[0].starts_with("no desk gated on \"nobody\""));
    }

    #[test]
    fn the_wrong_group_holding_the_desk_is_a_failure() {
        let (questions, aggregates) = site(FULL_DESK);
        let mut file = needs("");
        file.needs[0].handled_by = "sales".to_string();
        let findings = check(&file, &questions, &aggregates);
        assert_eq!(
            fails(&findings),
            vec!["no desk gated on \"sales\" reads \"projects\" - it is read by /desk (owners)"]
        );
    }

    #[test]
    fn via_pins_the_entry_alternative() {
        let (questions, aggregates) = site(FULL_DESK);
        let mut file = needs("");
        file.needs[0].via = Some("Follow along".to_string());
        let findings = check(&file, &questions, &aggregates);
        assert_eq!(
            fails(&findings),
            vec!["no path from \"/\" via \"Follow along\" records into \"projects\" within 2 submission(s)"]
        );
    }

    #[test]
    fn tasks_carry_the_page_as_a_choice_and_score_separates_misroutes() {
        let (questions, _) = site(FULL_DESK);
        let file = needs("");
        let tasks = tasks(&file, &questions, false);
        let skimmed = super::tasks(&file, &questions, true);
        assert_eq!(skimmed[0].questions["pick"].criteria["Follow along"], "Follow along");
        assert_eq!(tasks.len(), 1);
        let task = &tasks[0];
        assert_eq!(task.id, "founder@/");
        assert_eq!(task.expect, vec!["Hire us"]);
        let q = &task.questions["pick"];
        assert_eq!(q.kind, "choice");
        assert_eq!(q.criteria["Follow along"], "Notes by mail.");
        assert!(q.instructions.contains("What are you here for?"));

        let right = vec![Answer { id: "founder@/".into(), choice: "Hire us".into(), confidence: Some(0.55) }];
        let s = score(&tasks, &right, 0.6);
        assert_eq!((s.correct, s.misroutes.len(), s.hesitant.len()), (1, 0, 1));

        let wrong = vec![Answer { id: "founder@/".into(), choice: "Follow along".into(), confidence: Some(0.9) }];
        let s = score(&tasks, &wrong, 0.6);
        assert_eq!((s.correct, s.misroutes.len()), (0, 1));
        assert_eq!(s.accuracy(), 0.0);

        assert_eq!(score(&tasks, &[], 0.6).unanswered, vec!["founder@/"]);
    }
}